Gas turbine fuel mixer comprising a plurality of mini tubes for generating a fuel-air mixture

ABSTRACT

A mixer for blending fuel and air in a combustor of a turbine engine. The mixer includes a central body having a central passageway and a central axis. The mixer includes a plurality of tubes positioned radially around the central axis and circumferentially around a periphery of the mixer. Each of the tubes of the mixer includes opposed openings and a tangential opening. Each of the tubes of the mixer includes a cylindrical interior mixing passage configured to receive air flow from the opposed openings and the tangential opening and a fuel flow. The opposed openings are configured to spread the fuel flow laterally and the tangential opening is configured to spread the fuel flow tangentially.

TECHNICAL FIELD

The preferred embodiments relate to a fuel mixer. More particularly, thepreferred embodiments relate to a hydrogen fuel mini mixer with confinedtube cluster.

BACKGROUND

Presently, gas turbine engines are not capable of burning high hydrogenfuel blends. Mixers of the gas turbine engines present low-velocitypockets within the mixer that result in flashback (e.g., flame returningto the mixer) and flame-holding issues (e.g., flame within mixer),additionally fuel-air needs to be well mixed before exiting mixer toensure lower NOx emission.

BRIEF SUMMARY

According to an embodiment, a mixer for blending fuel and air in acombustor of a gas turbine engine, the mixer comprising: a central bodyhaving a central passageway and a central axis; a plurality of tubespositioned radially around the central axis and circumferentially arounda periphery of the mixer, each of the tubes comprising: a first openingangled with respect to the central axis and configured to introduce afirst air flow; a second opening in an opposed relationship with thefirst opening, the second opening angled with respect to the centralaxis and configured to introduce a second air flow; a tangential openingat an aft location to the first opening and second opening, thetangential opening angled with respect to the central axis andconfigured to introduce a tangential air flow; and a cylindricalinterior mixing passage configured to receive the first air flow, thesecond air flow, the tangential air flow, and a fuel flow, wherein thefirst air flow and the second air flow are configured to spread the fuelflow laterally and the tangential air flow is configured to spread thefuel flow tangentially, and wherein a fuel-air mixture is present at anexit of each of the plurality of tubes.

According to an embodiment, a mixer array for a turbine engine, themixer array comprising: a plurality of mixers, each mixer having acentral body and a plurality of mini tubes positioned circumferentiallyaround the central body, wherein each mini tube of the plurality of minitubes comprises a cylindrical mixing passage, an opposed air flowgenerated by air flows through opposing openings in the cylindricalmixing passage, and a tangential air flow generated by air flow througha tangential opening in the cylindrical mixing passage, wherein eachmini tube of the plurality of mini tubes is configured to blend a fuelflow with the opposed air flow and the tangential air flow, and whereinthe opposed air flow is configured to spread the fuel flow laterally andthe tangential air flow is configured to spread the fuel flowtangentially.

According to an embodiment, a method for mixing fuel in a gas turbineengine, the method comprising: injecting a natural gas fuel into the gasturbine engine to initiate operation of the gas turbine engine; afterinitiating operation, injecting a percentage by volume of hydrogen fuelwith the natural gas into a mixer for providing a fuel blend to the gasturbine engine; and ramping up the percentage by volume of hydrogen fuelto the range of 70% to 100% of the fuel blend, wherein the mixerprovides opposed air flow and tangential air flow to mix a flow of thefuel blend and to reduce low-velocity pockets in the mixer to reduceemissions.

Additional features, advantages, and embodiments of the preferredembodiments are set forth or apparent from consideration of thefollowing detailed description, drawings and claims. Moreover, it is tobe understood that both the foregoing summary of the preferredembodiments and the following detailed description are exemplary andintended to provide further explanation without limiting the scope ofthe embodiments as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages will be apparent fromthe following, more particular, description of various exemplaryembodiments, as illustrated in the accompanying drawings, wherein likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

FIG. 1 shows a schematic, cross-section view of a conventional mixer,according to an embodiment of the present disclosure.

FIG. 2A shows a schematic, cross-section view of a conventional mixer,according to an embodiment of the present disclosure.

FIG. 2B shows a schematic, perspective cross-section view of theconventional mixer of FIG. 2A, according to an embodiment of the presentdisclosure.

FIG. 3 shows a schematic view of a mixer array, according to anembodiment of the present disclosure.

FIG. 4A shows a schematic, cross-section view of a mixer, according toan embodiment of the present disclosure.

FIG. 4B shows a schematic of an end view of the outlet of the mixer ofFIG. 4A, according to an embodiment of the present disclosure.

FIG. 4C shows a schematic view taken along the section line A-A of themixer of FIG. 4A, according to an embodiment of the present disclosure.

FIG. 4D shows a schematic view of a tube for the mixer of FIG. 4A,according to an embodiment of the present disclosure.

FIG. 4E shows a schematic, cross-section view of the tube of FIG. 4D,according to an embodiment of the present disclosure.

FIG. 4F shows a schematic view of the tube of FIG. 4D taken along thesection line B-B having one tangential opening, according to anembodiment of the present disclosure.

FIG. 4G shows a schematic view of a tube similar to the tube of FIG. 4Dand taken along a section line equivalent to B-B having two tangentialopenings, according to an embodiment of the present disclosure.

FIG. 5 shows a schematic, cross-section view of a mixer, according to anembodiment of the present disclosure.

FIG. 6A shows a schematic of an array of mixers, according to anembodiment of the present disclosure.

FIG. 6B shows a schematic, cross-section view of a mixer, according toan embodiment of the present disclosure.

FIG. 6C shows a schematic, cross-section view of a mixer, according toan embodiment of the present disclosure.

FIG. 7A shows a schematic of an array of mixers, according to anembodiment of the present disclosure.

FIG. 7B shows a schematic, cross-section view of a mixer, according toan embodiment of the present disclosure.

FIG. 8 shows a schematic of an array of mixers, according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

Various embodiments of the preferred embodiments are discussed in detailbelow. While specific embodiments are discussed, this is done forillustration purposes only. A person skilled in the relevant art willrecognize that other components and configurations may be used withoutdeparting from the spirit and scope of the disclosure.

The mixer of the present disclosure is presented in the combustionsection of a gas turbine engine. The mixer may blend or mix the fuel andair prior to combustion. The mixer of the present disclosure may also beknown as a premixer. The mixer may reduce carbon emissions by allowingburn of pure hydrogen fuel (e.g., 100% hydrogen fuel) or a blend ofhydrogen fuel and natural gas (e.g., having a hydrogen percentagebetween 0% and 100%) through enhanced mixing with little or nolow-velocity regions and no flashback conditions. The mixer of thepresent disclosure provides for a mixer that may blend fuel and air inorder to achieve a uniform fuel-air distribution within the mixer andalso eliminate regions of low-velocity pockets within the mixer passage.This may allow for burning high H2 fuel while ensuring lower nitrogenoxide emissions.

The mixer of the present disclosure may include a circular tube mixer.The mixer of the present disclosure may include a set of opposed jetflow passages that may cause axially injected fuel introduced betweenthe set of opposed jet flow passages to increase lateral spread. Themixer of the present disclosure may include two tangential holes thatmay cause the injected fuel to spread tangentially in the tube therebyincreasing the fuel-air mixing within the tube. Thus, the mixer of thepresent disclosure may allow for a cluster of mini tubes where mixing ofthe fuel occurs with air. This may allow for compartmentalizing themixer and a more complex flow path, as compared to the prior art, thatmay improve fuel-air mixing within the tube, may reduce the flame flashback into the mini tubes, and/or may reduce flame-holding within themini tubes.

Referring to FIG. 1, a cross-section view of a conventional mixer 10 isshown. The mixer 10 may be included in a dry low emission (DLE) engine.The mixer 10 may include an outer vane 12 and an inner vane 14. Theouter vane 12 may include one or more openings 16. Fuel may be injectedor introduced through the one or more openings 16. The inner vane 14 mayinclude an opening 18. A swirling air flow may be injected or introducedthrough the opening 18. The swirling air flow from the inner vane 14 mayseparate on an outer surface of the center body 20. The passageways ofthe mixer 10 may be annular in cross-section as shown. The arrangementof the mixer 10 is not suitable for hydrogen (H2) fuels as thearrangement results in a re-circulation region on the outer surface ofthe center body 20 that may increase the flame-holding risk associatedwith H2 fuels. The length of the mixer 10 may be such that the residencetime of the fuel-air mixture within the mixer 10 may result in a highflame-holding risk. The mixer 10 may result in low-velocity zones nearthe vanes. An arrangement such as the mixer 10 may allow lower % volumeof H2 fuel blending in a fuel.

Referring to FIGS. 2A and 2B, cross-section views of a conventionalmixer 50 are shown. The mixer 50 may be included in a DLE engine. Themixer 50 may include an annular mixer passage 52. The fuel may beinjected from one or more openings 54 on frustrums 56. The mixer 50 mayfurther include a central bluff body 58. The central bluff body 58 maycreate an annular mixing passage as shown. The air flow for mixing withthe fuel may be provided with a separate air circuit. The mixer 50 mayallow higher % volume of H2 fuel blending in a fuel, as compared to themixer 10. As in the mixer 10, low-velocity zones may exist within themixer 50.

Referring to FIG. 3, a schematic, perspective view of a mixer array 100is shown. The mixer array 100 may include one or more mixers 102. Themixer array 100 may be divided into one or more zones. For example, inFIG. 2, the mixer array 100 may be divided into three zones: zone A,zone B, and zone C. The one or more mixers 102 provided in the zones A,B, and C may all be of the same construction, may all be of differentconstruction, or may include some mixers of the same construction andsome mixers of different construction.

FIGS. 4A-4E show a mixer 200 according to the present disclosure. Themixer 200 may be provided in the mixer array 100 of FIG. 3 (e.g., themixer 200 may take the place of one or more mixers 102 in the array 100of FIG. 3). Referring first to FIG. 4A, the mixer 200 may include one ormore tubes 202 (e.g., mini tubes) placed along a periphery of the mixer200. That is, the one or more tubes 202 may be placed circumferentiallyaround a central axis A of the mixer 200. The tubes 202 may representgenerally cylindrical mixer passages arranged as small circular tubes.The placement may be uniformly spaced or nonuniformly spaced about theperiphery of the mixer 200. The mixer 200 may include a central body204, also referred to as a central tube 204 having a central passage206. A first annular passage 208 and a second annular passage 210 may becreated between the central tube 204 and the one or more tubes 202. Thecentral tube 204 may include one or more openings 212 that fluidlycouple the central passage 206 to the second annular passage 210. One ormore passages 214 may fluidly couple the first annular passage 208 tothe one or more tubes 202, respectively. The one or more tubes 202 mayinclude an interior passage 218 and opposed openings 222, 216. One ormore openings 215 may fluidly couple the second annular passage 210 tothe one or more tubes 202. FIG. 4B shows an end view of the exit of themixer 200. An outlet 201 of each tube 202 may be seen in FIG. 4B. FIG.4C shows a view of the mixer 200 taken along the section line A-A ofFIG. 4A. The fuel-air mixing passage 218, the central passage 206, andthe second annular passage 210 are visible in the view of FIG. 4C.

Referring to FIGS. 4D-4G, one tube 202 of the mixer 200 is shown. Asmentioned, a plurality of tubes 202 may be placed around the peripheryof the mixer 200 (FIG. 4A). Each tube 202 may include the passage 214that has an opening 216, also referred to as an opposed opening 216, forfluidly coupling the first annular passage 208 (FIG. 4A) with theinterior passage 218 also referred to as a fuel-air mixing passage 218of the tube 202. The interior passage 218 may be circular incross-section (e.g., generally cylindrical passage as opposed to thegenerally annular mixing passage of FIGS. 1 and 2). The interior passage218 may be a fuel-air mixing passage. Each tube 202 may include a fuelpassage 220 that may exit into the interior passage 218. Each tube 202may include an opening 222, also referred to as an opposed opening 222,that opens into the interior passage 218. Each tube 202 may include anopening 224, also referred to as a tangential opening 224, that opensinto the interior passage 218.

Referring back to FIG. 4A, fuel flow A may be introduced or injectedaxially from a front end of the mixer 200 into the one or more fuelpassages 220 in the direction of arrow A. The fuel flow A may flow fromthe fuel passages 220 into the interior passage 218 (FIG. 4D) of thetube 202. Air may be introduced into the mixer 200 in a number oflocations. For example, a central air flow B may be introduced in thecentral passage 206 in the direction of the arrow B. The central airflow B may flow from the central passage 206, through the one or moreopenings 212, into the second annular passage 210 and exit through theopening 215 into the interior passage 218 of the tube 202. An air flow Cmay be introduced through the first annular passage 208 and may exitthrough the passage 214 into the interior passage 218 of the tube 202 inthe direction of arrow C. An air flow D, also referred to as an opposedair jet D and opposed air flow D, may be introduced through the opposedopening 222 into the interior passage 218 in the direction of arrow D.An air flow E, also referred to as a tangential air jet E and atangential air flow E, may be introduced through the tangential opening224 into the interior of the interior passage 218 in the direction ofarrow E.

The mixer 200 of FIGS. 4A-4G may present an air flow that allows forhigh velocity flows through the mixer 200. All flows A, B, C, D, and Emay converge in the interior passage 218. The first set of opposed jetflow (e.g., flows C and D) may push the fuel flow A into the centralarea of the interior passage 218 (e.g., may increase the lateral spreadof the fuel flow A) and may accelerate the velocity of the fuel flow A.The tangential air flow E may create a tangential flow/velocity thatcreates jets along the wall (e.g., as shown in FIGS. 4F and 4G) and maycause the fuel flow A to spread tangentially in the interior passage 218thereby increasing the fuel-air mixing within the tube 202. As shown inFIG. 4E, the tangential opening 224 may be positioned aft of the opposedopenings 216 and 222 to clean wakes created behind the jets.

Such an arrangement as shown in FIGS. 4A-4G may prevent or inhibitflame-holding. There may be a single tangential opening 224 (FIG. 4F) ortwo tangential openings 224 (FIG. 4G) to drive the fuel tangentially.More tangential openings (e.g., three or more) may be contemplated. Thetangential air flow may improve air-fuel mixing within the tube 202. Thetangential hole(s) may drive the fuel tangentially.

The tangential air flow E may be introduced at any angle (e.g., theangle of tangential openings 224) relative to the opposed openings 222.The included angle of the opposed openings 222 and 216 may be from about20 degrees to about 170 degrees, or any value or range therebetween. Thetangential hole(s) may be positioned aft of the opposed holes. Thisplacement may allow for cleaning of wakes behind the jets from theopposed holes and may generate high velocity near the tube wall, inaddition to assisting in mixing of the fuel and air.

Referring to FIG. 5, a mixer 300 is shown. The mixer 300 may be the sameor similar to the mixer 200 with the following differences. In the mixer300, the fuel flow A may be injected or introduced through the centralpassage 206 and then may be introduced to the interior passage 218radially. Opposed air flows C and D and tangential air flow E may bepresented in the same manner as FIG. 4 and may operate to increasemixing and accelerate the flow as otherwise described herein.Additionally, fuel flow A introduced through the central passage 206 mayenable the fuel to be discharged into different mini tube of a givenmixer at different axial location which in turn may help to achievedifferent fuel-air distribution at the exit of the mini tubes of a givenmixer. Such an arrangement may abate combustion dynamics.

Referring to FIGS. 6A-6C, a schematic of an array of mixers 400 isshown. Although four mixers 400 are shown, more or fewer may beprovided. The mixers 400 may be the same or similar to other mixersdescribed herein. In the array of mixers 400, one or more pilot tubes401 and one or more main tubes 402 may be provided. The pilot tubes 401may introduce the pilot fuel to the engine (e.g., fuel for initiatingthe engine) and the main tubes 402 may introduce the main fuel to theengine (e.g., fuel for operating the engine). The pilot fuel and themain fuel may be different. The pilot tubes 401 may allow for enhancedoperability, lower carbon monoxide emissions, and enhanced turn downcapability as compared to embodiments without one or more pilot tubes.The higher fuel-air ratio at the exit of the pilot tube(s) 401 may beachieved by independently controlling fuel flow through pilot circuit,reducing the length of the pilot tube(s) 401, injecting fuel at the aftend of the mixer 400, or any combination thereof. Each mixer may have afuel injector in the center that may act as a pilot tube. Although twopilot tubes 401 are shown, more or fewer may be provided, including nopilot tubes 401 being provided. Any location of pilot tubes 401 alongthe periphery of the mixer 400 may be provided. The location and numberof pilot tubes 401 may be the same or different in a mixer 400 ascompared to other mixers 400 in the array.

Referring to FIG. 6B, the pilot tube 401 a may be shorter with respectto the main tubes 402 a. The reduced length of the pilot tube 401 a ascompared to the main tube 402 a may result in different fueldistribution at the exit of the mixer.

Referring to FIG. 6C, the axial location of fuel injection may bedifferent for the pilot tube 401 b and the main tube 402 b. This maychange the heat release radially and circumferentially in a manner toinfluence combustion dynamics. For example, a main fuel may be injectedat A at a forward location with respect to the pilot fuel, with may beinject at B at an aft location. Separate fuel supply lines may beprovided to control fuel injection independently in the pilot tube 401 aand the main tube 402 b. The main tube 402 b may result in fuel airmixture that is more mixed than the pilot tube 401 b.

The pilot and main tubes of FIGS. 6B and 6C may be combined, may each beseparately provided in the array of FIG. 6A, or only one may be selectedto be placed in the arrange of FIG. 6A, or any combination thereof.Opposed air flows C and D and tangential air flow E may also bepresented in FIGS. 6B and 6C as previously described herein. Althoughtwo pilot tubes 401 are shown in FIG. 6A, any number of pilot tubes maybe provided at any location around the periphery of the mixer 400. Thesize of the openings and tube diameter may be smaller for the pilot tube401 to control pilot air flow from 2% to 20% of the total premixer flow.The size of each air and fuel opening for each tube may be different tochange the fuel-air ratio for different tubes to alter heat release forcombustion dynamics improvement.

Referring to FIGS. 7A and 7B, a schematic of an array of mixers 500 isshown. Although four mixers 500 are shown, more or fewer may beprovided. The mixers 500 may be the same or similar to other mixersdescribed herein. Each mixer 500, or one or more of the mixers 500, mayinclude fuel flow A injected in a center of the mixer (e.g., similar toFIG. 5) to act as a pilot. The array of mixers 500 may allow forenhanced operability, lower carbon monoxide emissions, and enhanced turndown capability as compared to mixers not provided with a pilot.Although the mixers 500 are shown to have pilot in the center, alternatelocations, such as, for example, but not limited to, a radial locationwithin a given mixer. The location of the pilot may be the same ordifferent for each mixer 500.

FIG. 8 shows a schematic of an array of mixers 600. Tubes 601 of themixer 600 may be staggered with respect to an adjacent mixer. Forexample, tube 601 a is out of alignment or staggered with respect totubes 601 b and 601 c. A similar arrangement is shown with respect tothe remaining tubes 601. Alternatively, the tubes 601 may be directedlyinline (e.g., as shown in FIG. 7A). A staggered alignment may improveemissions.

The mixer 10 of FIG. 1 may include a re-circulation zone on the centerbody 20 (FIG. 1) where high percentage hydrogen fuel may get trapped.This may result in flame-holding. Thus, the mixer 10 may not be able toburn higher H2 fuel content due to flashback/flame-holding risk.

As mentioned, the fuel may be injected axially near the center of themixer. Downstream of the first set of jets, the opposed jets may improvethe lateral spread of the fuel from the center of the mixer. Downstreamof the tangential jet, the tangential jet may improve the tangentialspread of the fuel from the center of the mixture. At the mixer exit,there may be uniform fuel distribution within the mixer having amixedness of fuel with the air of about 97%.

The mixer of the present disclosure creates shorter flame length (ascompared to a mixer such as described in FIGS. 1 and 2) and a uniformtemperature in the combustor. The flame length is about 50% shortercompared to the flame length in the mixer of FIGS. 1 and 2. Theincreased mixedness of the fuel and air and the reduction or eliminationof low-velocity pockets may result in the shorter flame length, achievemore uniform temperature in the combustor, reduceflashback/flame-holding risk, or any combination thereof.

The mixers of the present disclosure may be a mini mixer having acluster of minitubes (e.g., a cluster of tubes) having a center axisplaced at a radial location with respect to the center of the mixer thatis greater than 0.8 times the inner mixer outer diameter. Each of thetubes (e.g., minitubes) may have a cylindrical confinement with aconstant area section in the front end and a converging section at theback end. This arrangement may maintain high velocity within the tube.The array of such mixers may form different zones within combustor(e.g., as shown in FIG. 2).

The mixer of the present disclosure may allow for fuel to be injectedaxially on a slanted or angled surface where the fuel may be blasted byair moving on a slanted or angled surface (e.g., from the tangentialhole(s)) and by opposed air (e.g., from the opposing holes). The fuelmay also be injected from the center body in constant area section. Themixer of the present disclosure may include a mixer tip having a centralregion that may be cooled by air, fuel, or a combination thereof, beforethe same is exhausted into mixer passage.

The mixer of the present disclosure may include multiple small tubesthat may generate small compact flames, thereby increasing residencetime in the post flame zone that may lower carbon monoxide emissions, ascompared to prior art mixers.

The mixer of the present disclosure may be oriented such that tubes on aparticular mixer may be directly inline or staggered with respect to thetubes of an adjacent mixer. Such an arrangement may improve emissions.

The mixer of the present disclosure has applications in aero-derivativeengines, other gas turbine engines, and applications outside of the gasturbine application. The mixer of the present disclosure may reduceand/or eliminate carbon emissions by allowing burn of varying blends ofhydrogen fuel.

The hydrogen fuel percentage may vary from a volume percentage of thefuel blend between 0% to 100%. The hydrogen fuel percentage may varyfrom a volume percentage of the fuel blend between 10% to 100%. Thehydrogen fuel percentage may vary from a volume percentage of the fuelblend between 20% to 100%. The hydrogen fuel percentage may vary from avolume percentage of the fuel blend between 30% to 100%. The hydrogenfuel percentage may vary from a volume percentage of the fuel blendbetween 40% to 100%. The hydrogen fuel percentage may vary from a volumepercentage of the fuel blend between 50% to 100%. The hydrogen fuelpercentage may vary from a volume percentage of the fuel blend between60% to 100%. The hydrogen fuel percentage may vary from a volumepercentage of the fuel blend between 70% to 100%. The hydrogen fuelpercentage may vary from a volume percentage of the fuel blend between80% to 100%. The hydrogen fuel percentage may vary from a volumepercentage of the fuel blend between 90% to 100%. The hydrogen fuelpercentage may vary from a volume percentage of the fuel blend between55% to 95%. The hydrogen fuel percentage may vary from a volumepercentage of the fuel blend between 60% to 90%. The hydrogen fuelpercentage may vary from a volume percentage of the fuel blend between65% to 85%. The hydrogen fuel percentage may vary from a volumepercentage of the fuel blend between 70% to 80%. The hydrogen fuelpercentage may vary from a volume percentage of the fuel blend between85% to 100%. The hydrogen fuel percentage may vary from a volumepercentage of the fuel blend between 95% to 100%. The hydrogen fuelpercentage may vary from a volume percentage of the fuel blend of about55%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%. The mixer of thepresent disclosure may allow for burning of 100% hydrogen fuel in anengine.

The mixer of the present disclosure may allow for burning of naturalgas, high hydrocarbon (C2+) fuel, hydrogen, or any combination thereof.The burning of the aforementioned fuels or combinations thereof maylower NOx emissions as compared to prior art mixers. The burning of upto 100% hydrogen fuel capability may allow for zero carbon footprint.

The fuel flow of the present disclosure may represent fuel provided forthe engine. The fuel flow may be a pure fuel flow (e.g., pure naturalgas, pure hydrogen, etc.) or may be a blended fuel flow (e.g., apercentage by volume of two or more fuels, such as, for example, naturalgas and hydrogen). The mixer of the present disclosure may be providedin an engine that may be started with natural gas fuel having nohydrogen fuel mixed therein, then hydrogen fuel may be blended into thenatural gas fuel and ramped up to 70%-100% of the fuel mixture at alower power condition to reduce the carbon monoxide emissions. Then, thehydrogen fuel percentage may be reduced at a higher power condition toabout 50% of the fuel mixture to achieve lower nitrogen oxide emissions.The mixer may be operated with 100% hydrogen fuel throughout engineoperation (e.g., at low and high-power conditions). The particular fuelblend (e.g., including any percentage of hydrogen from 0% to 100%) mayallow for lower NOx and CO emissions.

The mixer of the present disclosure may provide an air-fuelmixture/ratio that may remove auto-ignition, flash-back, andflame-holding risk normally associated with a pure premixed burner/mixerdesign with high hydrogen fuel blends. The mixer of the presentdisclosure may be presented to generate an arrange of compact andswirled flames.

The mixer of the present disclosure may allow for an aero-derivative,100% hydrogen fueled, DLE engines. This may allow up to 100% hydrogencapability (zero carbon footprint) for merging with renewables, whilerequiring little or no water for meeting lower NOx emissionsrequirements.

Further aspects of the present disclosure are provided by the subjectmatter of the following clauses.

1. A mixer for blending fuel and air in a combustor of a gas turbineengine, the mixer comprising: a central body having a central passagewayand a central axis; a plurality of tubes positioned radially around thecentral axis and circumferentially around a periphery of the mixer, eachof the tubes comprising: a first opening angled with respect to thecentral axis and configured to introduce a first air flow; a secondopening in an opposed relationship with the first opening, the secondopening angled with respect to the central axis and configured tointroduce a second air flow; a tangential opening at an aft location tothe first opening and second opening, the tangential opening angled withrespect to the central axis and configured to introduce a tangential airflow; and a cylindrical interior mixing passage configured to receivethe first air flow, the second air flow, the tangential air flow, and afuel flow, wherein the first air flow and the second air flow areconfigured to spread the fuel flow laterally and the tangential air flowis configured to spread the fuel flow tangentially, and wherein afuel-air mixture is present at an exit of each of the plurality oftubes.

2. The mixer of any preceding clause, wherein the fuel flow isintroduced axially to the cylindrical interior mixing passage along eachof the tubes from a forward end of the mixer.

3. The mixer of any preceding clause, wherein the fuel flow isintroduced to the cylindrical interior mixing passage at a forwardlocation with respect to the first air flow, the second air flow, andthe tangential air flow.

4. The mixer of any preceding clause, further comprising a third airflow introduced through the central passageway, through an annularpassage between the central body and the plurality of tubes, and intothe cylindrical interior mixing passage.

5. The mixer of any preceding clause, wherein the tangential openingcomprises two tangential openings.

6. The mixer of any preceding clause, wherein the fuel flow isintroduced axially to the central passageway of the central body from aforward end of the mixer.

7. The mixer of any preceding clause, wherein the fuel flows from thecentral passageway to an annular passageway formed between the pluralityof tubes and the central body and to the cylindrical interior mixingpassage.

8. The mixer of any preceding clause, wherein the fuel flow isintroduced to the cylindrical interior mixing passage at an aft locationto the first air flow, the second air flow, and the tangential air flow.

9. The mixer of any preceding clause, wherein at least one tube of theplurality of tubes is a pilot tube and the remaining tubes of theplurality of tubes are main tubes.

10. The mixer of any preceding clause, wherein the pilot tube comprisesa pilot cylindrical interior mixing passage that is shorter in axiallength than a main cylindrical interior mixing passage of the maintubes.

11. The mixer of any preceding clause, wherein the fuel flow isintroduced to the pilot tube at a forward location in the mixer withrespect to the fuel flow introduced into the main tubes.

12. The mixer of any preceding clause, wherein there is no low-velocityregion within each of the cylindrical interior mixing passage of theplurality of tubes.

13. A mixer array for a turbine engine, the mixer array comprising: aplurality of mixers, each mixer having a central body and a plurality ofmini tubes positioned circumferentially around the central body, whereineach mini tube of the plurality of mini tubes comprises a cylindricalmixing passage, an opposed air flow generated by air flows throughopposing openings in the cylindrical mixing passage, and a tangentialair flow generated by air flow through a tangential opening in thecylindrical mixing passage, wherein each mini tube of the plurality ofmini tubes is configured to blend a fuel flow with the opposed air flowand the tangential air flow, and wherein the opposed air flow isconfigured to spread the fuel flow laterally and the tangential air flowis configured to spread the fuel flow tangentially.

14. The mixer array of any preceding clause, wherein, in each mixer ofthe plurality of mixers, the fuel flow is introduced axially to thecylindrical mixing passage of each of the mini tubes from a forward endof the mixer.

15. The mixer array of any preceding clause, wherein, in each mixer ofthe plurality of mixers, the fuel flow is introduced to the cylindricalmixing passage at a forward location with respect to the opposed airflow and the tangential air flow.

16. The mixer array of any preceding clause, wherein, in each mixer ofthe plurality of mixers, the fuel flow is introduced axially to thecentral body from a forward end of the mixer.

17. The mixer array of any preceding clause, wherein, in each mixer ofthe plurality of mixers, at least one mini tube of the plurality of minitubes is a pilot tube and the remaining mini tubes of the plurality ofmini tubes are main tubes.

18. The mixer array of any preceding clause, wherein a mini tube of afirst mixer of the plurality of mixers is directly aligned with a minitube of a second mixer of the plurality of mixers.

19. The mixer array of any preceding clause, wherein a mini tube of afirst mixer of the plurality of mixers is staggered and out of alignmentwith a mini tube of a second mixer of the plurality of mixers.

20. A method for mixing fuel in a gas turbine engine, the methodcomprising: injecting a natural gas fuel into the gas turbine engine toinitiate operation of the gas turbine engine; after initiatingoperation, injecting a percentage by volume of hydrogen fuel with thenatural gas into a mixer for providing a fuel blend to the gas turbineengine; and ramping up the percentage by volume of hydrogen fuel to therange of 70% to 100% of the fuel blend, wherein the mixer providesopposed air flow and tangential air flow to mix a flow of the fuel blendand to reduce low-velocity pockets in the mixer to reduce emissions.

21. The method of any preceding clause, wherein the opposed air flow isprovided from a pair of opposed openings and the tangential air flow isprovided from a tangential opening, the pair of opposed openings and thetangential opening each being angled with respect to a central axis ofthe mixer.

22. The method of any preceding clause, wherein the opposed air flow andthe tangential air flow are provided in a cluster of mini tubes providedaround a periphery of the mixer.

23. The method of any preceding clause, wherein the tangential air flowis introduced aft to the opposed air flow.

24. The method of any preceding clause, wherein the opposed air flow isconfigured to spread the flow of the fuel blend laterally and thetangential air flow is configured to spread the flow of the fuel blendtangentially.

Although the foregoing description is directed to the preferredembodiments, it is noted that other variations and modifications will beapparent to those skilled in the art, and may be made without departingfrom the spirit or scope of the present disclosure. Moreover, featuresdescribed in connection with one embodiment may be used in conjunctionwith other embodiments, even if not explicitly stated above.

What is claimed is:
 1. A mixer for blending fuel and air in a combustorof a gas turbine engine, the mixer comprising: a central body having acentral passageway and a central axis; a plurality of tubes positionedradially around the central axis and circumferentially around aperiphery of the mixer, each of the tubes comprising: a first openingangled with respect to the central axis and configured to introduce afirst air flow; a second opening in an opposed relationship with thefirst opening, the second opening angled with respect to the centralaxis and configured to introduce a second air flow; a tangential openingat an aft location to the first opening and second opening, thetangential opening angled with respect to the central axis andconfigured to introduce a tangential air flow; and a cylindricalinterior mixing passage configured to receive the first air flow, thesecond air flow, the tangential air flow, and a fuel flow, wherein thefirst air flow and the second air flow are configured to spread the fuelflow laterally and the tangential air flow is configured to spread thefuel flow tangentially, and wherein a fuel-air mixture is present at anexit of each of the plurality of tubes.
 2. The mixer of claim 1, whereinthe fuel flow is introduced axially to the cylindrical interior mixingpassage along each of the tubes from a forward end of the mixer.
 3. Themixer of claim 2, wherein the fuel flow is introduced to the cylindricalinterior mixing passage at a forward location with respect to the firstair flow, the second air flow, and the tangential air flow.
 4. The mixerof claim 1, further comprising a third air flow introduced through thecentral passageway, through an annular passage between the central bodyand the plurality of tubes, and into the cylindrical interior mixingpassage.
 5. The mixer of claim 1, wherein the tangential openingcomprises two tangential openings.
 6. The mixer of claim 1, wherein thefuel flow is introduced axially to the central passageway of the centralbody from a forward end of the mixer.
 7. The mixer of claim 6, whereinthe fuel flows from the central passageway to an annular passagewayformed between the plurality of tubes and the central body and to thecylindrical interior mixing passage.
 8. The mixer of claim 7, whereinthe fuel flow is introduced to the cylindrical interior mixing passageat an aft location to the first air flow, the second air flow, and thetangential air flow.
 9. The mixer of claim 1, wherein at least one tubeof the plurality of tubes is a pilot tube and the remaining tubes of theplurality of tubes are main tubes.
 10. The mixer of claim 9, wherein thepilot tube comprises a pilot cylindrical interior mixing passage that isshorter in axial length than a main cylindrical interior mixing passageof the main tubes.
 11. The mixer of claim 9, wherein the fuel flow isintroduced to the pilot tube at a forward location in the mixer withrespect to the fuel flow introduced into the main tubes.
 12. The mixerof claim 1, wherein there is no low-velocity region within each of thecylindrical interior mixing passage of the plurality of tubes.
 13. Amixer array for a turbine engine, the mixer array comprising: aplurality of mixers, each mixer having a central body and a plurality ofmini tubes positioned circumferentially around the central body, whereineach mini tube of the plurality of mini tubes comprises a cylindricalmixing passage, an opposed air flow generated by air flows throughopposing openings in the cylindrical mixing passage, and a tangentialair flow generated by air flow through a tangential opening in thecylindrical mixing passage, wherein each mini tube of the plurality ofmini tubes is configured to blend a fuel flow with the opposed air flowand the tangential air flow, and wherein the opposed air flow isconfigured to spread the fuel flow laterally and the tangential air flowis configured to spread the fuel flow tangentially.
 14. The mixer arrayof claim 13, wherein, in each mixer of the plurality of mixers, the fuelflow is introduced axially to the cylindrical mixing passage of each ofthe mini tubes from a forward end of the mixer.
 15. The mixer array ofclaim 14, wherein, in each mixer of the plurality of mixers, the fuelflow is introduced to the cylindrical mixing passage at a forwardlocation with respect to the opposed air flow and the tangential airflow.
 16. The mixer array of claim 13, wherein, in each mixer of theplurality of mixers, the fuel flow is introduced axially to the centralbody from a forward end of the mixer.
 17. The mixer array of claim 13,wherein, in each mixer of the plurality of mixers, at least one minitube of the plurality of mini tubes is a pilot tube and the remainingmini tubes of the plurality of mini tubes are main tubes.
 18. The mixerarray of claim 13, wherein a mini tube of a first mixer of the pluralityof mixers is directly aligned with a mini tube of a second mixer of theplurality of mixers.
 19. The mixer array of claim 13, wherein a minitube of a first mixer of the plurality of mixers is staggered and out ofalignment with a mini tube of a second mixer of the plurality of mixers.20. A method for mixing fuel in a gas turbine engine, the methodcomprising: injecting a natural gas fuel into the gas turbine engine toinitiate operation of the gas turbine engine; after initiatingoperation, injecting a percentage by volume of hydrogen fuel with thenatural gas into a mixer for providing a fuel blend to the gas turbineengine; and ramping up the percentage by volume of hydrogen fuel to therange of 70% to 100% of the fuel blend, wherein the mixer providesopposed air flow and tangential air flow to mix a flow of the fuel blendand to reduce low-velocity pockets in the mixer to reduce emissions.